Plug-in diffusers are known in the art. Such diffusers are plugged directly into wall sockets and generate heat to facilitate the diffusion of an active material, such as air freshener or insect control material. Such diffusers are also known as heat-assisted evaporative dispensers. One particular type of plug-in diffuser employs a liquid or gel air-treating composition in an enclosure, all or part of which is formed of a polymeric film. When heated, the air-treating composition can migrate through the polymeric film to be released as a vapor at an outer surface. The use of this type of permeable polymeric membrane controls the dispensing of air-treating vapors, and tends to eliminate great variations in rate of dispensing over the life of the product. Another conventional type of plug-in diffuser employs a liquid air freshener, such as scented oil, contained in a clear plastic container or bottle. A plug-in scented oil diffuser is described in, for example, U.S. Pat. No. 5,647,053.
Various types of fragrance dispensers, other than the evaporative type, are also known in the art. With respect to the many devices known for dispensing fragrance, U.S. Pat. No. 5,382,410 discloses an electrostatic vapor/aerosol generator for supplying aromatic oil, deodorant, disinfectant, fumigant, fungicide, insecticide or bactericide to a room. U.S. Pat. No. 4,702,418 discloses an adjustable aerosol dispenser for supplying different amounts of a fragrance into a room according to sensed light, odor, sound, etc., within the room. U.S. Pat. No. 5,115,975 discloses a device for emitting a vaporized substance into the atmosphere according to the setting of a timer. U.S. Pat. No. 6,135,369 discloses an electrostatic sprayer which can spray insecticides, which can be controlled according to selected on times and off times, and which incorporates a sensor to sense the available power for continued operation. U.S. Pat. No. 4,689,515 discloses an ultrasonic liquid atomizer with automatic frequency control. U.S. Pat. Nos. 3,543,122 and 3,615,041 disclose aerosol dispensers having timers for controlling the operation of the dispensers according to preset times.
Also, additional dispensers of the type often referred to as plug-in diffusers are described in U.S. Pat. Nos. 4,849,606, 5,937,140, and 6,478,440, which are assigned to S.C. Johnson & Son, Inc., of Racine, Wis. In particular, it is noted that U.S. Pat. No. 6,478,440 (“the '440 patent”), which is incorporated herein by reference, discloses a fragrance warmer incorporating plug-through capability and an incandescent nightlight. The combination of incandescent bulbs and fragrance dispensers in plug-in devices has proven popular.
Incandescent nightlights, however, suffer from various disadvantages. For example, incandescent bulbs produce considerable heat. When incandescent nightlights are used in connection with a diffuser of volatile active material, the heat generated by the incandescent nightlight tends to affect the rate at which the active material is diffused. Thus, when the nightlight is turned on, the active material may, for example, be diffused too quickly. Also, because of the added heat, it is difficult to regulate the rate at which an active material is diffused.
Another disadvantage of using incandescent bulbs as nightlights is that they tend to consume relatively large amounts of energy. Since nightlights are often left on for extended periods of time in multiple rooms of a house, this energy consumption can be a significant consideration.
Various techniques, such as using different incandescent bulbs and using bulbs of varying size or power rating, have been tried in order to reduce the heat produced and the power consumed by nightlights. These techniques, however, have yielded only mild reductions in heat emission and energy consumption, and come at a cost to performance of the nightlight.
Recently, several documents have suggested reducing the power consumption of a nightlight by using a light emitting diode (LED) as the light source of the nightlight. For example, U.S. Patent Application Publication No. 2002/0075677 discloses a nightlight using a number of LEDs as the light source, arranged in series with a current-limiting capacitor.
In addition, lighting devices which emit different colored light, such as from LEDs are generally known, as demonstrated with respect to the use of multiple LEDs in a single unit, as disclosed in U.S. Pat. No. 6,149,283.
Furthermore, U.S. patent application Ser. No. 10/212,746, assigned to S.C. Johnson & Son, Inc., which was filed on Dec. 5, 2002, discloses a liquid vaporizer including a nightlight, wherein the nightlight may be an incandescent lamp, a neon lamp, or an LED device. None of the foregoing documents, however, describes a preferred combination of a plug-in diffuser and a low-temperature, low-power nightlight, which provides sufficient light, is long lasting, is inexpensive to manufacture, and is easy to use, in the manner of our invention.
Another problem with conventional plug-in diffusers is that they do not make effective use of lighting elements. For example, lighting elements in conventional diffusers are typically not used to generate aesthetic lighting displays, such as multicolored displays, color-changing displays, projection displays, shine-through displays, or the like.
A still further problem is that conventional plug-in diffusers are limited in their use to locations where wall sockets are already exist. Wall sockets are often located in places that are less than ideal for placement of diffusers, such as near the floor, in a corner, etc. This limitation on the location of plug-in diffusers is even more problematic for diffusers that have a lighting element or display, since the diffuser often cannot be located in a user's line of sight, thereby limiting the effectiveness of the lighting element.
Yet another problem is that conventional diffusers typically do not have suitable controllability for varying the emission of light and/or fragrance. In particular, such plug-in diffusers seldom include fragrance dispensers that are easily and precisely adjustable to vary a fragrance intensity or diffusion rate, such as, for example, piezoelectric fragrance dispensing pumps.
Thus, a need exists in the art for a plug-in diffuser that resolves these and other problems in the prior art.